The emission spectra of red, green, and blue phosphors that define the additive primary colors of a CRT color video display

Primary colors are sets of colors that can be combined to make a useful range (gamut) of colors. For human applications, three are often used; for additive combination of colors, as in overlapping projected lights or in CRT displays, the primary colors normally used are red, green, and blue. For subtractive combination of colors, as in mixing of pigments or dyes, such as in printing, the primaries normally used are magenta, cyan, and yellow.^[1] This article is about the book. ... Primary Colors is a 1998 film starring John Travolta based on the popular book (a success in part fueled by speculation over the identity of the author). ... Image File history File links Download high-resolution version (2444x1591, 71 KB) Spectra of individual color phosphors of a typical CRT video monitor. ... Image File history File links Download high-resolution version (2444x1591, 71 KB) Spectra of individual color phosphors of a typical CRT video monitor. ... A materials emission spectrum is the amount of electromagnetic radiation of each frequency it emits when it is heated (or more generally when it is excited). ... Green screen A phosphor is a substance that exhibits the phenomenon of phosphorescence (sustained glowing after exposure to light or energised particles such as electrons). ... CRT can mean: Cathode Ray Tube, in electronics, a display device (such as those used in one type of television) C Run-Time, in computing Charitable Remainder Trust, in Law Chinese Remainder Theorem, in mathematics Corneal Refractive Therapy, in medicine Criterion-referenced test, in U.S. schools Critical race theory... Color is an important part of the visual arts. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... For other uses, see Red (disambiguation). ... For other uses, see Green (disambiguation). ... This article is about the colour. ... Magenta is a color made up of equal parts of red and blue light. ... Cyan (from Greek κυανοs, meaning blue) may be used as the name of any of a number of a range of colors in the blue/green part of the spectrum. ... This article is about the color. ...

Any choice of primary colors is essentially arbitrary; for example, an early color photographic process, autochrome, typically used orange, green, and violet primaries.^[2] A box of Autochrome plates, expiry date 1923. ... See also Orange (disambiguation) for other meanings of the word. ... For other uses, see Green (disambiguation). ... Violet (named after the flower violet) is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nanometres (this is a spectral color). ...

Biological basis

Primary colors are not a fundamental property of light but are often related to the physiological response of the eye to light. Fundamentally, light is a continuous spectrum of the wavelengths that can be detected by the human eye, an infinite-dimensional stimulus space.^[3] However, the human eye normally contains only three types of color receptors called cone cells. Each color receptor responds to different ranges of the color spectrum. Humans and other species with three such types of color receptors are known as trichromats. These species respond to the light stimulus via a three-dimensional sensation, which can generally be modeled as a mixture of three primary colors.^[3] This article deals with the general meaning of spectrum and the history of its use. ... For other uses, see Wavelength (disambiguation). ... In physiology, a stimulus is a detectable change in the internal or external environment. ... Normalized responsivity spectra of human cone cells, S, M, and L types Cone cells, or cones, are photoreceptor cells in the retina of the eye which function best in relatively bright light. ... A trichromat is an organism for which the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no more than three different pure spectral lights. ... It has been suggested that this article or section be merged with Sensation and perception psychology. ...

Species with different numbers of receptor cell types would have color vision requiring a different number of primaries. For example, for species known as tetrachromats, with four different color receptors, one would use four primary colors. Since humans can only see to 400 nanometers (violet), but tetrachromats can see into the ultraviolet to about 300 nanometers, this fourth primary color might be located in the shorter-wavelength range. A tetrachromat is an organism for which the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no more than four different pure spectral lights. ... A nanometre (American spelling: nanometer) is 1. ... Violet (named after the flower violet) is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nanometres (this is a spectral color). ... For other uses, see Ultraviolet (disambiguation). ...

Many birds and marsupials are tetrachromats, and it has been suggested that some human females are tetrachromats as well^[4][5], having an extra variant version of the long-wave (L) cone type.^[6] The peak response of human color receptors varies, even amongst individuals with “normal” color vision^[7]; in non-human species this polymorphic variation is even greater, and it may well be adaptive^[8]. Most mammals other than primates have only two types of color receptors and are therefore dichromats; to them, there are only two primary colors. For other uses, see Bird (disambiguation). ... This article is about mammals. ... A tetrachromat is an organism for which the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no more than four different pure spectral lights. ... Dichromacy in humans is a moderately severe color vision defect in which one of the three basic color mechanisms is absent or not functioning. ...

It would be incorrect to assume that the world 'looks tinted' to an animal (or human) with anything other than the human standard of three color receptors. To an animal (or human) born that way, the world would look normal to it, but the animal's ability to detect and discriminate colors would be different from that of a human with normal color vision. If a human and an animal both look at a natural color, they see it as natural; however, if both look at a color reproduced via primary colors, for example on a color television screen, the human may see it as matching the natural color, while the animal does not; in this sense, reproduction of color via primaries must be "tuned" to the color vision system of the observer. See TV (disambiguation) for other uses and Television (band) for the rock band European networks National In much of Europe television broadcasting has historically been state dominated, rather than commercially organised, although commercial stations have grown in number recently. ...

Additive primaries

Additive color mixing

The sRGB color triangle

Main article: Additive color

Media that combine emitted lights to create the sensation of a range of colors are using the additive color system. Typically, the primary colors used are red, green, and blue. Image File history File links AdditiveColor. ... Image File history File links AdditiveColor. ... The title given to this article is incorrect due to technical limitations. ... Additive color mixing: adding red to green yields yellow; adding yellow to blue yields white. ... Additive color mixing: adding red to green yields yellow; adding yellow to blue yields white. ...

Television and other computer and video displays are a common example of the use of additive primaries and the RGB color model. The exact colors chosen for the primaries are a technological compromise between the available phosphors (including considerations such as cost and power usage) and the need for large color triangle to allow a large gamut of colors. The ITU-R BT.709-5/sRGB primaries are typical. RGB redirects here. ... Green screen A phosphor is a substance that exhibits the phenomenon of phosphorescence (sustained glowing after exposure to light or energised particles such as electrons). ... The title given to this article is incorrect due to technical limitations. ...

CIE 1931 RGB color triangle with monochromatic primaries

Additive mixing of red and green light produces shades of yellow, orange, or brown.^[9] Mixing green and blue produces shades of cyan, and mixing red and blue produces shades of purple and magenta. Mixing nominally equal proportions of the additive primaries results in shades of grey or white; the color space that is generated is called an RGB color space. Image File history File links Download high resolution version (1140x1260, 350 KB) CIE 1931 xy chromaticity diagram including the gamut for the CIE 1931 RGB space and the E white point Please see Image:CIExy1931. ... Image File history File links Download high resolution version (1140x1260, 350 KB) CIE 1931 xy chromaticity diagram including the gamut for the CIE 1931 RGB space and the E white point Please see Image:CIExy1931. ... This article is about the color. ... See also Orange (disambiguation) for other meanings of the word. ... For other uses, see Brown (disambiguation). ... This article is about the color. ... Magenta is a color made up of equal parts of red and blue light. ... Achromatic redirects here. ... This article is about the color. ... A comparison of different color spaces. ... An RGB color space is any additive color space based on the RGB color model. ...

The CIE 1931 color space defines monochromatic primary colors with wavelengths of 435.8 nm (violet), 546.1 nm (green) and 700 nm (red). The corners of the color triangle are therefore on the spectral locus, and the triangle is about as big as it can be. No real display device uses such primaries, as the extreme wavelengths used for violet and red result in a very low luminous efficiency. In the study of the perception of color, one of the first mathematically defined color spaces was the CIE XYZ color space (also known as CIE 1931 color space), created by the International Commission on Illumination (CIE) in 1931. ... Something which is monochromatic has a single color. ... Luminous efficiency is a measure of the proportion of the energy supplied to a lamp that is converted into light energy. ...

Subtractive primaries

Main article: Subtractive color

Media that use reflected light and colorants to produce colors are using the subtractive color method of color mixing. Subtractive color mixing An 1877 color photo by Louis Ducos du Hauron, a French pioneer of color photography. ... Subtractive color mixing An 1877 color photo by Louis Ducos du Hauron, a French pioneer of color photography. ...

Traditional

Main article: RYB color model

RYB (red, yellow, and blue) is a historical set of subtractive primary colors. It is primarily used in art and art education, particularly painting.^[10] It predates modern scientific color theory. Mixture of RYB primary colors RYB (an abbreviation of red-yellow-blue) is a historical set of subtractive primary colors. ... For other uses , see Painting (disambiguation). ... In the arts of painting, graphic design, and photography, color theory is a body of practical guidance to color mixing and the visual impact of specific color combinations. ...

Standard RYB Color Wheel

RYB make up the primary color triad in a standard color wheel; the secondary colors VOG (violet, orange, and green) make up another triad. Triads are formed by 3 equidistant colors on a particular color wheel; neither RYB nor VOG are equidistant on a perceptually uniform color wheel, but rather have been defined to be equidistant in the RYB wheel.^[11] Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Boutets 7-color and 12-color color circles from 1708. ... A secondary color is a color made by mixing two primary colors in a given color space. ...

Painters have long used more than three “primary” colors in their palettes—and at one point considered red, yellow, blue, and green to be the four primaries^[12]. Red, yellow, blue, and green are still widely considered the four psychological primary colors^[13], though red, yellow, and blue are sometimes listed as the three psychological primaries ^[14], with black and white occasionally added as a fourth and fifth ^[15].

During the 18th century, as theorists became aware of Isaac Newton’s scientific experiments with light and prisms, red, yellow, and blue became the canonical primary colors—supposedly the fundamental sensory qualities that are blended in the perception of all physical colors and equally in the physical mixture of pigments or dyes. This theory became dogma, despite abundant evidence that red, yellow, and blue primaries cannot mix all other colors, and has survived in color theory to the present day.^[16] Sir Isaac Newton FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ...

Using red, yellow, and blue as primaries yields a relatively small gamut, in which, among other problems, colorful greens, cyans, and magentas are impossible to mix, because red, yellow, and blue are not well-spaced around a perceptually uniform color wheel. For this reason, modern three- or four-color printing processes, as well as color photography, use cyan, yellow, and magenta as primaries instead.^[17] Most painters include colors in their palettes which cannot be mixed from yellow, red, and blue paints, and thus do not fit within the RYB color model. Some who do use a three-color palette opt for the more evenly spaced cyan, yellow, and magenta used by printers, and others paint with 6 or more colors to widen their gamuts.^[18] The cyan, magenta, and yellow used in printing are sometimes known as "process blue," "process red," "process yellow."^[19] In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ...

CMYK color model, or four-color printing

Main article: CMYK color model

In the printing industry, to produce the varying colors the subtractive primaries cyan, magenta, and yellow are applied together in varying amounts. Before the color names cyan and magenta were in common use, these primaries were often known as blue-green and purple, or in some circles as blue and red, respectively, and their exact color has changed over time with access to new pigments and technologies.^[20] Cyan, magenta, yellow, and key (black). ... Cyan (from Greek κυανοs, meaning blue) may be used as the name of any of a number of a range of colors in the blue/green part of the spectrum. ... Magenta is a color made up of equal parts of red and blue light. ... This article is about the color. ...

Subtractive color mixing – the magenta and cyan primaries are sometimes called purple and blue-green, or red and blue

Mixing yellow and cyan produces green colors; mixing yellow with magenta produces reds, and mixing magenta with cyan produces blues. In theory, mixing equal amounts of all three pigments should produce grey, resulting in black when all three are applied in sufficient density, but in practice they tend to produce muddy brown colors. For this reason, and to save ink and decrease drying times, a fourth pigment, black, is often used in addition to cyan, magenta, and yellow. Image File history File links SubtractiveColor. ... Image File history File links SubtractiveColor. ... Optical density is the absorbance of an optical element for a given wavelength λ per unit distance: Where: Although absorbance does not have true units, it is quite often reported in Absorbance Units or AU. Accordingly, optical density is measured in ODU, which are equivalent to AU cm−1. ... For other uses, see Brown (disambiguation). ... This article is about the color. ...

The resulting model is the so-called CMYK color model. The abbreviation stands for cyan, magenta, yellow, and key—black is referred to as the key color, a shorthand for the key printing plate that impressed the artistic detail of an image, usually in black ink.^[21] Cyan, magenta, yellow, and key (black). ... An abbreviation (from Latin brevis short) is a shortened form of a word or phrase. ... In printing, a key plate was the plate which printed the detail in an image. ...

In practice, colorant mixtures in actual materials such as paint tend to be more complex. Brighter or more saturated colors can be created using natural pigments instead of mixing, and natural properties of pigments can interfere with the mixing. For example, mixing magenta and green in acrylic creates a dark cyan—something which would not happen if the mixing process were perfectly subtractive. For other uses, see Paint (disambiguation). ... It has been suggested that this article or section be merged with Chromaticity. ... A Bigger Splash, 1967. ...

In the subtractive model, adding white to a color, whether by using less colorant or by mixing in a reflective white pigment such as zinc oxide, does not change the color’s hue but does reduce its saturation. Subtractive color printing works best when the surface or paper is white, or close to it. Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ... An image with the hues cyclically shifted The hues in the image of this Painted Bunting are cyclically rotated with time. ...

A system of subtractive color does not have a simple chromaticity gamut analogous to the RGB color triangle, but a gamut that must be described in three dimensions. There are many ways to visualize such models, using various 2D chromaticity spaces or in 3D color spaces.^[22]

Four "pure" colors

Pure colors based on the opponent process model of color perception, red, yellow, green, and blue, are often augmented with black and white to describe the full range of colors.

Psychovisual studies and the opponent process color model lead to the notion of four "pure" or "unique" colors:^[23] red, yellow, green, and blue, with red and green defining one color-opponent axis, and yellow and blue a second color-opponent axis. Image File history File links Opponent_colors. ... Image File history File links Opponent_colors. ... Opponent colors based on experiment. ... Psychophysics is a subdiscipline of psychology dealing with the relationship between physical stimuli and their subjective correlates, or percepts. ... Opponent colors based on experiment. ...

In this model, there is no physical mixing process, such as additive or subtractive, to say exactly how colors combine to make other colors.

See also

• Color theory
• Secondary color
• Tertiary color
• Visual perception

In the arts of painting, graphic design, and photography, color theory is a body of practical guidance to color mixing and the visual impact of specific color combinations. ... A secondary color is a color made by mixing two primary colors in a given color space. ... A tertiary color is a color made by mixing one primary color with one secondary color, in a given color space. ... In psychology, visual perception is the ability to interpret information from visible light reaching the eyes. ...

Notes and references

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... See also Rayleigh fading Rayleigh scattering Rayleigh number Rayleigh waves Rayleigh-Jeans law External links Nobel website bio of Rayleigh About John William Strutt MacTutor biography of Lord Rayleigh Categories: People stubs | 1842 births | 1919 deaths | Nobel Prize in Physics winners | Peers | British physicists | Discoverer of a chemical element ... is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 226th day of the year (227th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 226th day of the year (227th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...

External links

• Handprint : do "primary" colors exist? – a comprehensive site on color primaries, color perception, color psychology, color theory and color mixing.
• Ask A Scientist: Primary Colors
• The Color-Sensitive Cones at HyperPhysics
• Color Tutorial